1. Field of the Invention
The present invention relates to a door mirror for use with vehicles and more particularly, it relates to a door mirror of the electrically swingable type wherein a mirror housing projected outside the car body can be automatically swung and collapsed along the car body by remote control in the car room.
2. Prior Art
Door mirrors for use with vehicles are usually attached to the car body, projecting outside the car body. The mirror for use in the door mirror is a plane mirror or mirror having a small curvature. In addition, that position of the door mirror which is attached to the car body is near to the visual point of the driver. In order to get the same rear sight as in the case of the fender mirrors whose mirrors are of the convex type, therefore, it is needed that the mirror in the door mirror is made larger-sized. The door mirror housing in which the mirror is housed is thus large-sized and this results in that the door mirrors are projected outside the car body.
When the door mirrors are projected outside the car body like this, however, there is a danger that matters and persons may contact the door mirrors to cause unexpected accident while driving the car.
Further, when cars or vehicles provided with the door mirrors are to be transported, they occupy larger space because of their door mirrors and this makes their transportation cost higher. In addition, their door mirrors sometimes hinder them from coming into and out of garages.
In order to solve these problems, preliminarily-opened Japanese Utility Model Application Sho 61-125849 has proposed a door mirror of the electrically swingable type. FIG. 1 shows the door mirror of this type.
According to the door mirror, a mirror housing 1 is swingably pivoted on a center shaft 3 which is fixed to a base 2, and it is swung, relative to the base 2, round the center shaft 3 by a driver system which includes a motor 4 arranged in the mirror housing 1. The mirror housing 1 is thus collapsed toward and along the car body. More specifically, when the motor 4 rotates, a sun-and-planet gear 6 which serves as the clutch system at the upper portion of the mirror housing is rotated through a speed reduction system in a case 5 to run round a sun gear 7 which is fixed to the upper portion of the center shaft 3. The mirror housing 1 is thus swung relative to the base 2.
The support of the mirror housing 1 and base 2 is attained in such a way that a bearing section 8 of the case 5 in which the driver system in the mirror housing 1 is housed is fitted onto a cylindrical shaft section 10 of a shaft holder 9, which is fixed to the base 2, through a washer 11. This causes the case 5 which houses the driver system therein to be supported only the bearing section 8 of the shaft holder 9 arranged on the base 2. In other words, the case 5 is supported in the cantilever manner. When the car vibrates, therefore, the mirror housing 1 resonates with the vibration of the car, thereby making it difficult to see rear sight through the door mirrors.
Further, the sealing between the bearing section 8 and the cylindrical shaft section 10 is not sufficient. Therefore, there is the possibility that grease injected into the case 5 to smooth the driver system leaks outside from between the bearing section 8 and the cylindrical shaft section 10 of the shaft holder 9.
Furthermore, the driver system housed in the case 5 includes the speed reduction system which comprises five stages of gears connected to the motor, as shown in FIG. 2. A large-diameter gear 12, small-diameter gear 13 and shaft 14 are combined one another as a unit and the same thing can be said about other gears. The small-diameter gear 13 is engaged with the large-diameter gear 12 of the next stage while a small-diameter gear 15 of the final stage is engaged with a gear 6a of planet gear means 6. This means that the speed reduction system includes many shafts and bearing sections for the gears. Therefore, engaging errors are likely to be created between the gears. This hinders the gears from being smoothly rotated and thus causes noises. In addition, the speed reduction system must be large-sized.
Two planet gears 6a and 6b which also serves as the clutch system are made concave and convex on their opposite faces, which make them engageable with each other. They are urged by a compression spring 16 and a push nut 17 and engaged with each other at their concave and convex faces. When overload is applied to the upper planet gear 6b, the upper planet gear 6b runs idle relative to the lower planet gear 6a to thereby prevent the driver system from being damaged. The upper planet gear 6b is lifted in this case while rotating and the coil spring 16 is thus rotated to rotate the push nut 17. As the result, the push nut 17 comes out of a shaft 18 because clearance between the push nut 17 and the shaft 18 is made larger.